1. Field of the Invention
The present invention relates to techniques of distributing a captured image from an image distribution apparatus to an image receiving apparatus.
2. Related Background Art
An image distribution system is known which outputs an image in a field-of-view range set by a user. An example of such a system is disclosed, for example, in Japanese Patent Application Laid-open No. H10-136347 (Patent Document 1). In this system, a client having a control right controls panning, tilting and zooming of a camera which mounts a zoom controllable optical system and a pan/tilt mechanism such as an electrically driven universal head. According to this control, the camera can capture and output an image in a designated field-of-view range.
Another example is a system including an image distribution apparatus capable of electronical operation of panning, tilting and zooming. For example, refer to Japanese Patent Application Laid-open No. H09-261522 (Patent Document 2). This image distribution apparatus cuts out an image in a field-of-view range designated by a client, from an image captured by using an optical system having a wide field-of-view. Cut-out images are output as an image stream (hereinafter called a distribution image) of consecutive still images or moving images. The optical system having a wide angle-of-view includes an omni directional mirror, a fisheye lens or a quasi wide angle lens having a plurality of lenses disposed adjacent to each other.
With the structure described in Patent Document 1, only one client having a control right can designate basically a field-of-view range at a time. The image distribution apparatus described in Patent Document 2 adopts the structure shown in FIG. 2 of Patent Document 2. Namely, if each of a plurality of distribution image generating units for executing an image cut-out process can generate a distribution image independently from other distribution image generating units, images having different angle-of-view ranges can be distributed to a plurality of clients.
There is no system which has the structure shown in FIG. 2 of Patent Document 2, can manage exclusive rights permitting to set a field-of-view range, as field-of-view range setting rights, and can allow only a client given the field-of-view range setting right to set a field-of-view range. If this system is realized, the field-of-view range setting right can be given at a time to n clients at the maximum.
A client not having the field-of-view range setting right can receive the same distribution image as that of a client having the field-of-view range setting right. However, with the structure described in Patent Document 1, only one distribution image is generated always so that it is impossible to select a field-of-view by selecting the distribution image. In contrast, with the structure described in Patent Document 2, the field-of-view can be selected by selectively receiving one of the n distribution images at the maximum. However, in order to realize the system described above, it is necessary to manage field-of-view range setting rights and clients in addition to a dedicated GUI. Using only the structures described in Patent Documents 1 and 2 is insufficient.